First things first, Cthulhu sent me this for free, They didn't tell me they were sending it and they didn't ask me to do a review in return, post links or ask for anything in return at all. ... and this isn't a review, it just me starting a thread for us to discuss the item, I've not used it anywhere near enough yet to give a realistic 'rating' anyway.... so that out of the way. When I posted this in the 'what did you get you the mail' the discussion started about the mech/regulated situation. To be honest I wasn't sure what 'protections' this mod had so I asked Cthulhu some questions so I could get some info to pass on, because I knew I would be getting asked. What I gather from our conversation is that the circuit board contains a mosfet switching system and some kind of diode protection that acts like a fuse and will blow with an atomister hard short or if the resistance is under 0.1ohm. It also has reverse battery protection should you put the battery in the wrong way. There is no '5 clicks' on or off, no led, no power regulation. In use it is very much like using a mech, using the voltage of the cell only. If you get a short and blow the protection on the board you will need to replace the PCB, Cthulhu have assured me that these will be available as replacements at an 'affordable cost' and knowing the price of Cthulhu products and spares I have no doubt this will be the case. Thankfully the PCB is very easy to replace, there's just a single 1.5mm hex screw to undo. Back at the other end, there's some more safety features, inside the tubes are delrin (?) rings, which hold the case of the battery away from the sides of the metal tubes by just a fraction. In 18350 mode there's one at the top and bottom of the cell, in 18650 there's top, middle and bottom. There's also 2 large holes in the bottom (in the battery tightening section) to allow safer venting of the battery if that should happen. (it's positive down for the cell, so they are in exactly the right place) Here's some pics of how it looks in 18350 and 18650 modes, with 22mm and 24mm atties. and some size comparisons.. If there's one thing that I'm not too keen on it's this little octopus, which looks like a kids cartoon or something..... not sure why they decided to go with that when personally I think the usual Cthulhu logo is cool and would have looked much better and would have matched the one on the hastur chamber. ... odd choice. anyway that's about it, let me know what you think. (we can just ignore the octopus if you like!) I've been enjoying it so far, it does feel like i'm using a mech (with a nicer button placement) it's pretty heavy and solid feeling too. Thanks @cthulhumod any questions?